DIN EN 3774-004:2014-10

Standard series EN 3774 describes requirements for three-pole circuit breakers, temperature compensated with a rated current from 1 A to 25 A, used in aircraft on-board circuits. The new edition of Part 004 specifies the characteristics of three-pole circuit breakers with UNC thread terminals, temperature compensated with a rated current from 1 A to 25 A, used in aircraft on-board circuits at a temperature between -55 °C and 125 °C for ratings less than or equal to 15 A and -55 °C to 90 °C for ratings greater than 15 A and at a maximum altitude of 22 000 m. These circuit breakers are operated by a push-pull type single pushbutton (actuator) with delayed action "tripfree" tripping. They will continue to function up to the short-circuit current. The following modifications have been made with respect to the previous edition DIN EN 3774-004:1999-08: a) the scope has been extended to include rated currents up to 1 A, the indications of switching capacity and the intended use with electrical supplies in accordance with EN 2282 have been deleted; b) normative references have been modified; c) layout and content of the standard have been significantly modified and extended: previous Clause 4 "Requirements" has been replaced by Clause 4 "Dimensions and mass" and Clause 5 "Characteristics", the subclauses containing information on fasteners have been replaced by a reference to EN 6113; d) besides numerous additional indications regarding material, surface treatment, mechanical characteristics and environmental conditions, Subclause 5.4 has been added containing different tables with electrical requirements; e) for the purpose of the identity block according to Clause 6, Clause 7 with Table 8 containing rated current codes and Clause 8 containing delivery codes have been incorporated; f) extended marking requirements have been introduced in Clause 9 and Clause 10 and a statement of the technical specifications has been incorporated. The standards of the EN 3774 series are prepared by ASD-STAN, Technical Section Electrics, with the participation of German experts of the Aerospace Standards Committee. The European Committee for Standardization (CEN) declared the Aerospace and Defence Industries Association of Europe (ASD-STAN) responsible for the preparation of European standards (EN) for the field of aerospace. The responsible German standardization committee is Working Committee NA 131-04-05 AA "Schalter, Relais und Schutzgeräte" ("Switch, relays and protection devices") of the Aerospace Standards Committee (NL) at DIN.